Cruise stop in Shanghai

Hi, we are UK citizens travelling from the UK and visiting Shanghai in March via P&O round the world cruise. We are scheduled to spend 2 days in Shanghai and we return to the ship overnight in port. Our previous port of call will be Manila (Philippines) and after leaving Shanghai on the same ship, we will travel to Hong Kong.

Our son lives and works in Shanghai and we wish to visit him (and look around Shanghai) rather than go on an organised excursion with P&O cruises. Do we qualify for the 144-Hour Visa-Exemption Transit and how do we apply for this/what documents do we require?

Thanks Rob